DENVER (AP) — Denver teachers are prepared to walk of the job Monday for the first time in 25 years over an incentive-based pay system they call unpredictable and unfair to experienced educators.

If teachers get their way in a last-minute deal or after a strike, it could be the warm-up for their greater influence over how city schools are funded. Denver teachers are taking a different approach than the recent strike in Los Angeles and the wave of teacher activism nationwide since last spring, which also prioritized ways to improve schools, not just pay raises.

Teachers in Los Angeles went on strike last month for higher pay but ended up getting the same 6 percent raise offered early on by the nation’s second-largest school district. However, they also sought and won promises for smaller class sizes and adding more nurses and counselors.

Denver’s more than 4,000 teachers have a narrower focus on raises because a contract recently expired for their incentive pay system, which governs bonuses for working in high-poverty schools and other things and has been touted by education reformers. The cost of living also has risen dramatically in the booming city and shifting demographics have quickly transformed schools ranked as high poverty into ones with fewer low-income students.

Bonuses paid to teachers with more than 14 years of experience do not become part of their base pay, which critics say encourages high turnover and hurts students. Both sides have agreed to get rid of that provision but disagree about how big the bonuses should be for two key categories — teachers working in high-poverty schools and in schools deemed high priority by the district.

The union is pushing for lower bonuses for those categories to free up more money for overall teacher pay. However, the district sees those bonuses as key to boosting the academic performance of poor and minority students.

Some teachers who have worked in high-poverty schools say bonuses are not what keep them in the job. They say spending money on smaller class sizes and adding support staff, like counselors, is the best way to help students learn and make them good schools to work in.

Those issues will not be decided until the teachers’ overall contract expires in two years.

Elementary school teacher Chris Christoff said he hopes a win on teacher pay will put them in a better position to negotiate those issues, as teachers in Los Angeles did.

“We’re showing the district we are going to stand up for what we need. In two years, we’re going to do the same,” he said.

Both Christoff and colleague Hannah Simon have lost bonuses by leaving schools where they say teaching wasn’t fun or meaningful because of administrators.

They have lost bonus pay again because their school is no longer considered high poverty in a neighborhood where luxury townhouses and apartments are going up. But they plan to stay because their principal is committed to doing whatever she can to keep class sizes low.

“My pay has flat-lined because of having to make really hard decisions,” Simon said.

Teachers are in the position to flex their muscle because Gov. Jared Polis decided Wednesday against intervening to stop the strike, saying both sides were not far apart on a deal.

The Democrat, who founded charter schools for disadvantaged students and wants to increase overall school funding in the state, did say he may step in if a strike drags on.

It would cost an estimated $400,000 a day to keep school operating with substitutes and administrators. He acknowledged that a prolonged strike would not help a plan to eventually ask voters for more money for education in a state that lags behind despite a booming economy.

“There is no question that in the eyes of the voters who matter, dysfunction will not be rewarded,” Polis said.